BenzWorld Junior Member
Date registered: Jan 2009
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exhaust manifold heater flap (thermo spiral)
1958 220S sedan
Got the two new thermo spirals installed, following the MBZponton page, and the workshop manual instructions. Was careful to put the spirals on in the correct direction shown in the instructions, and to add some tension as instructed.
Engine cold, the flaps are open inside the manifold, allowing warm air to heat up the intake manifold. Weights are rotated out toward the fender, and "at rest". Normal.
Took the car for a nice long drive; engine fully warmed up. Opened the hood, and found the flaps *still* in the open (cold) position. Flap weights still down (flap open), rotated out toward fender. Goosed the throttle a couple times to increase manifold pressure, but no change in the flap weights.
They're completely free to turn with hand pressure against the spiral tension, but the spirals actually seem to hold them open, and not allow them to close for normal warm operation. When the spirals heat up, they get tighter (more tension).
Any suggestions? Seems the spiral should just barely hold the flap open, then tighten under heat and allow the flap to close. But to do that, you have to install the spiral opposite to the workshop manual instructions.